This invention relates to the preparation of 1,3-propanediol. In a specific aspect, the invention relates to the recovery of 1,3-propanediol from a reaction product mixture containing carbonyl impurities.
1,3-Propanediol (PDO) is an important industrial chemical useful in the preparation of poly(propylene terephthalate) (PPT), a polyester from which films and fibers can be made. PDO can be prepared from ethylene oxide in a process involving cobalt-catalyzed hydroformylation followed by hydrogenation, and it can alternatively be prepared by hydrolysis of acrolein in the presence of an acid catalyst followed by hydrogenation. In the preparation of PDO, it is common for the crude product to include 400 ppm or more carbonyl by-products including acetals. High levels of carbonyl impurities in PDO are associated with the production of acrolein during preparation of PPT and with poor color in fibers spun from the PPT.
It is therefore an object of the invention to provide a process for purifying 1,3-propanediol. In one aspect, it is an object of the invention to provide a process which reduces the carbonyl content of PDO and reduces the amount of acrolein by-product in the condensation polymerization to PPT.